Many operations have destructive variants that side effect an input sequence, instead of creating a new sequence:

Constructive	Destructive
suffix	suffix!
remove	remove!
remove-eq	remove-eq!
remove-nth	remove-nth!
reverse	reverse!
append	append!
map	map!
filter	filter!

Changing elements:

map! ( ... seq quot: ( ... elt -- ... newelt ) -- ... seq )

change-nth ( ..a i seq quot: ( ..a elt -- ..b newelt ) -- ..b )

Deleting elements:

remove! ( elt seq -- seq )

remove-eq! ( elt seq -- seq )

remove-nth! ( n seq -- seq )

delete-slice ( from to seq -- )

delete-all ( seq -- )

filter! ( ... seq quot: ( ... elt -- ... ? ) -- ... seq )

Adding elements:

suffix! ( seq elt -- seq )

append! ( seq1 seq2 -- seq1 )

Other destructive words:

reverse! ( seq -- seq )

move ( to from seq -- )

exchange ( m n seq -- )

copy ( src i dst -- )

Related Articles
When to use destructive operations
Treating sequences as stacks

See also
set-nth, push, push-all, pop, pop*